The possibility of degradation of the tryptophan biosynthetic enzymes will be investigated under various conditions of culture starvation in a constitutive strain of Escherichia coli. Missense mutants containing altered tryptophan synthetase alpha polypeptide will also be studied. Degradation of these proteins will be examined in various mutants believed to be affected in intracellular proteolysis. Radioactively labeled polypeptides will be examined by sodium dodecyl sulfate, acrylamide gel electrophoresis following immunoprecipitation. The missense alpha polypeptides will initially be screened by an enzyme complementation test. Genetic manipulations will be by standard phage transduction procedures. The results of these studies relate to cellular adaptation and differentiation and have potential significance to both aging and cancer.